@Priest72 some do and some don't, they're like fixies as @luetage said. They need to be in order to balance, so you can move the wheel back or forward underneath your body -- much like a track stand. You actually have a lot of control when the pedals are not on a freewheel, you can control your descent down a hill or decelerate as you approach a stop by resisting the pedals. That way you're not heating up your brakes and wearing them down. When people put a brake on a fixie it's typically only the front wheel, where 80-90% of your stopping power is, and they're really for emergency stops. If you stop the pedals moving, the rear tire is going to skid. If you just slam on the brake, you're going over the handlebars; you gotta shift your body weight behind the bike to avoid that. In an emergency stop, you'll use the front brake, stop the rear wheel, skid it out to the side & steer the front wheel forward while your body weight is low & behind the bike. If you don't have a fixie, you likely have brakes on both wheels, and always, emergency or no, want to engage the rear first -- it can be near simultaneous though. You should shift your weight back behind the saddle when descending big hills as well, to avoid the aforementioned flipping over the bars, if your front wheel hits a pothole or something you don't want a lot of weight on it.
Happy riding!
Edit: PS - We watch a lot of cycling. I'm not sure how I got so lucky as to find a partner who is perhaps more into watching cycling more than I am. Right now, because the pandemic messed up the season, two of the grand tours are going on concurrently. The Giro is almost over, while the Vuelta is about a week in. Actually, the Giro might have just ended yesterday, but we're a few stages behind in our watching of that race. We like bikes. (@luetage, in case you didn't know but want to)
